Pure lead is a silvery-white metal that oxidizes and turns bluish-gray when exposed to air. Lead is primarily used in the manufacture of lead-acid batteries, lead alloys, lead oxides in pigments, glass, lead cable coating, and a variety of lead products including ammunition and radiation shielding. Lead is emitted into the atmosphere from mining and smelting; from its use as a feedstock in the production of lead alloys, lead compounds and other lead-containing products; from mobile sources; and from combustion sources. The major sources of Pb emissions have historically been motor vehicles and industrial sources.